Heavy metal poisoning remains a public health concern despite efforts to eliminate heavy metal usage. While efforts to remove tetraethyl lead from gasoline, paint and other consumer products have helped reduce body loading of lead, environmental exposure to lead persists in paint chips, dust and lead-containing kitchenware such as glass, ceramic glazes and metallic foils.
Mercury represents another heavy metal that tends to bioaccumulate. Mercury exposure has been traced to contaminants found within coal and are noted to bioaccumulate, especially in fish.
The symptoms of heavy metal poisoning are well known, including especially deleterious effects suffered by children. Upon identification of high heavy metal loadings within an individual, lifestyle changes and the administration of chelation agents serve to minimize the deleterious effects. However, these treatments can only be put in place after testing of an individual for heavy metal.
While various public health organizations and agencies have been successful in performing universal and routine testing of children for heavy metal poisoning, large numbers of individuals are never tested or tested at a frequency that is less than ideal. Compliant testing for heavy metals has met with limited success owing in part to the necessity for a blood draw requiring skilled personnel, parental consent, blood draw trauma to the child, and sophisticated infrastructure to process samples. Saliva has previously been studied as an attractive alternative bodily fluid for the measurement of heavy metal concentrations. However, attempts to correlate salivary lead with that found in blood, bone marrow or fatty tissue have proven inconsistent.
Thus, there exists a need for a saliva-based assay for heavy metals in order to increase screening, especially of children. Additionally, there exists a need for a reproducible saliva sample collection methodology to facilitate correlation between blood and saliva heavy metal concentrations.